The invention relates to a blade fuse formed by assembling a fuse element into a housing, the fuse element interposing a fusible portion between a pair of flat metal terminals.
A blade fuse (hereinafter referred to as "the fuse") has a fuse element (hereinafter referred to as "the element") formed by interposing a fusible portion between a pair of flat metal terminals (hereinafter referred to as "the terminals") and is assembled with the base end portion of the element (the base end portion being an end portion having the fusible portion formed thereon) accommodated in a housing. Such a blade fuse addresses the problem that the fusible portion that is not rigid is susceptible to deform or break due to external force applied to the terminals.
An exemplary blade fuse that has overcome such a problem is disclosed in Japanese Patent Examined Publication No. Hei. 1-45174. This blade fuse will be described with reference to FIGS. 5 to 7. FIG. 5 is an exploded perspective view showing the conventional fuse before being assembled; FIG. 6 is a perspective view shoeing the conventional fuse as assembled, part of which is depicted in phantom line; and FIG. 7 is an enlarged view showing a hinge portion for forming a continuous flap.
A fusible portion 5 is interposed between terminals 3a and 3b of an element 1. The fusible portion 5 connects the terminals 3a and 3b to each other electrically and constructively. Since the fusible portion 5 has a predetermined sectional area, it is difficult to give the fusible portion 5 a rigidity exceeding a predetermined value.
On the other hand, a flap 9 is arranged in the middle of an inserting opening of a housing 7 into which the terminals 3a and 3b are inserted. The flap 9 is formed continuously to the housing 7 through a thin-walled hinge 11 (see FIG. 7) with the base end of the flap 9 capable of turning.
In the thus constructed conventional fuse 13, the operation of assembling the element 1 to the housing 7 is performed in the following manner. The base end portion of the element 1 is inserted into the housing 7, and this causes the flap 9 to turn. Through this turn, the flap 9 is retained by projections 15 formed on the terminals 3a and 3b to be fixed between the terminals 3a and 3b. As a result, the fuse 13 is assembled with the terminals 3a and 3b held in the housing 7, preventing external force from concentrating on the fusible portion 5.
Thus, according to the conventional fuse 13, the external force can be borne by the flap 9. This does not allow the external force to concentrate on the fusible portion 5, thus preventing the fusible portion 5 from being deformed or broken by the external force.
However, since the flap 9 that prevents deformation or breakage of the fusible portion 5 is formed continuously to the housing 7 through the thin-walled hinge 11 in the conventional fuse 13, the rigidity of the flap 9 is poor. As a result, the terminals 3a and 3b cannot be fixed reliably. In addition, the formability of the thin-walled hinge 11 is not satisfactory, which impairs productivity. Moreover, the fixing of the terminals using the flap 9 requires the additional step of causing the flap 9 to be retained by the projections 15 while turning the flap 9 after the element 1 has been inserted into the housing 7. This makes the assembling operation cumbersome.